Antenna control unit and phased-array antenna

ABSTRACT

A paraelectric transmission line layer and a ferroelectric transmission line layer are laminated through a ground conductor, and plural phase shifters, which are connected via through holes that pass through the ground conductor, are disposed on both of the transmission line layers at some positions on a feeding line that branches off from the input terminal between all antenna terminals and an input terminal to which a high-frequency power is applied. In addition, loss elements each having the same transmission loss amount as the phase shifter, or the phase shifters are disposed so that transmission loss amounts from all of the antenna terminals to the input terminal are equalized. Accordingly, an antenna control unit which can be manufactured in fewer manufacturing processes and has a pointed beam and a large beam tilt amount, and a phased-array antenna that employs such an antenna control unit are provided.

TECHNICAL FIELD

The present invention relates to an antenna control unit that employs aferroelectric as a phase shifter, and a phased-array antenna thatutilizes such an antenna control unit. More particularly, the presentinvention relates to an antenna control unit such as mobile unitidentifying radio or automobile collision avoidance radar, and aphased-array antenna that utilizes such an antenna control unit.

BACKGROUND ART

Systems such as “Active phased-array antenna and antenna control unit”described in Japanese Published Patent Application No. 2000-236207(hereinafter, referred to as Prior Art 1) have been suggested asexamples of conventional phased-array antennas that employ aferroelectric as a phase shifter.

Hereinafter, a conventional phased-array antenna will be described withreference to FIGS. 9 and 10.

Initially, operating principles of a conventional phase shifter aredescribed with reference to FIGS. 9( a) and 9(b). FIGS. 9( a) and 9(b)are diagrams illustrating a phase shifter 700 that is suggested in theconventional phased-array antenna. FIG. 9( a) is a diagram illustratinga construction of the phase shifter 700, and FIG. 9( b) is a diagramshowing permittivity changing characteristics of a ferroelectricmaterial.

This phase shifter 700 includes a microstrip hybrid coupler 703 thatemploys a paraelectric material 701 as a base material, and a microstripstub 704 that employs a ferroelectric material 702 as a base materialand is formed adjacent to the microstrip hybrid coupler 703. This phaseshifter 700 is constituted such that a phase shift amount of ahigh-frequency power that passes through the microstrip hybrid coupler703 varies according to a DC control voltage which is applied to themicrostrip stub 704.

In other words, the base material of the phase shifter 700 is composedof the paraelectric material 701 and the ferroelectric material 702. Arectangular loop-shaped conductor layer 703 a is disposed on theparaelectric base material 701, and this loop-shaped conductor layer 703a and the paraelectric base material 701 form the microstrip hybridcoupler 703.

Further, two linear conductor layers 704 a 1 and 704 a 2 are disposed onthe ferroelectric base material 702 so as to be located on extensionlines of two opposed linear parts 703 a 1 and 703 a 2 of the rectangularloop-shaped conductor layer 703 a and linked to one of the ends of thetwo linear parts 703 a 1 and 703 a 2, respectively. These two linearconductor layers 704 a 1 and 704 a 2 and the ferroelectric base material702 form the microstrip stub 704.

Further, conductor layers 715 a and 720 a are disposed on theparaelectric base material 701 so as to be located on extension lines ofthe two linear parts 703 a 1 and 703 a 2 and linked to the other ends ofthe two linear parts 703 a 1 and 703 a 2, respectively.

This conductor layer 715 a and the paraelectric base material 701 forman input line 715, and the conductor layer 720 a and the paraelectricbase material 701 form an output line 720.

Here, the one end and the other end of the linear part 703 a 1 on theloop-shaped conductor layer 703 a are ports 2 and 1 of the microstriphybrid coupler 703, respectively. On the other hand, the one end and theother end of the linear parts 703 a 2 of the loop-shaped conductor layer703 a are ports 3 and 4 of the microstrip hybrid coupler 703,respectively.

In the phase shifter 700 having the above-mentioned construction, whenthe DC control voltage is applied to the microstrip stub 704, the phaseshift amount of the high-frequency power that passes therethroughvaries.

Hereinafter, a detailed explanation of the phase shifter 700 will begiven. In the phase shifter 700 having such a construction in which onereflection element (microstrip stub 704) is connected to the adjacenttwo ports (ports 2 and 3) of the properly-designed microstrip hybridcoupler 703, a high-frequency power that enters from the input port(port 1) is not outputted from the input port 1, but the high-frequencypower upon which a power reflected from the reflection element has beenreflected is outputted only from the output port (port 4). In thereflection from the microstrip stub 704 as the reflection element, abias field 705 that is produced by the control voltage is in the samedirection as that of a field produced by the high-frequency power thatpasses through the microstrip stub 704, as shown in FIG. 9( a).Therefore, as shown in FIG. 9( b), when the control voltage is changed,an effective permittivity of the microstrip stub 704 with respect to thehigh-frequency power varies adaptively. Accordingly, the equivalentelectrical length of the microstrip stub 704 for the high-frequencypower varies, and the phase on the microstrip stub 704 is changed.

In the case of common ferroelectric base materials, the bias voltage 705that is required to change the effective permittivity of the microstripstub 704 is in a rage of several kilovolts/millimeter to a dozenkilovolts/millimeter. Accordingly, a high frequency is not produced bythe effective permittivity that is affected by a field formed by thehigh-frequency power which passes through the microstrip stub 704.

Next, a construction of the conventional phased-array antenna and itsoperating principles will be described with reference to FIGS. 10( a)and 10(b).

FIG. 10( a) is a diagram illustrating a construction of the conventionalphased-array antenna 830, and FIG. 10( b) is a diagram showingdirectivities of the conventional phased-array antenna 830 in a casewhere a beam tilt voltage is applied and a case where the beam tiltvoltage is not applied.

The conventional phased-array antenna 830 comprises plural antennaelements 806 a-806 d which are placed in a row at regular intervals on adielectric base material, an antenna control unit 800, and a beam tiltvoltage 820. The antenna control unit 800 comprises a feeding terminal808 to which a high-frequency power is applied (hereinafter, referred toas an input terminal), a high frequency blocking element 809, and pluralphase shifters 807 a 1-807 a 4.

In this conventional phased-array antenna 830, the antenna element 806 ais connected to the input terminal 808, the antenna element 806 b isconnected to the input terminal 808 through one phase shifter 807 a 1,the antenna element 806 c is connected to the input terminal 808 throughtwo phase shifters 807 a 3 and 807 a 4, and the antenna element 806 d isconnected to the input terminal 808 through three phase shifters 807 a2, 807 a 3, and 807 a 4, by means of a feeding line (hereinafter,referred to as a transmission line), respectively. The beam tilt voltage820 is connected to the input terminal 808 through the high frequencyblocking element 809.

It is assumed here that each construction of the phase shifters 807 a1-807 a 4 is the same as that described with reference to FIG. 9, andthe phase shifters 807 a 1-807 a 4 have the same characteristics.

In the phased-array antenna 830 having the above construction, thenumber of phase shifters 807 which are located between one of theantenna elements 806 a-806 d and the input terminal 808 is one largerthan the number of phase shifters 807 which are located between theadjacent antenna element 806 and the input terminal 808, respectively,and further, all of the phase shifters 807 have the samecharacteristics. Therefore, as shown in FIG. 10( b), the control of theantenna's directivity (beam tilt) is performed by one beam tilt voltage820.

The control of the antenna directivity will be described in more detail.For example, assuming that each of the phase shifters 807 a 1-807 a 4delays the phase of the high-frequency power that passes through eachphase shifter by a phase shift amount Φ and the adjacent phase shifters807 are spaced by a distance d, respectively, the high-frequency powerthat has entered the antenna element 806 a is supplied to the inputterminal 808 with no phase change, as shown in FIG. 10( a). In contrastto this, the high-frequency power that has entered the antenna element806 b is supplied to the input terminal 808, with its phase beingdelayed by the phase shifter 807 a 1 by a phase shift amount Φ. Thehigh-frequency power that has entered the antenna element 806 c issupplied to the input terminal 808, with its phase being delayed by thephase shifters 807 a 3 and 807 a 4, by a phase shift amount 2Φ. Further,the high-frequency power that has entered the antenna element 806 d issupplied to the input terminal 808, with its phase being delayed by thephase shifters 807 a 2, 807 a 3, and 807 a 4, by a phase shift amount3Φ.

In other words, a direction of the maximum sensitivity for radio wavesreceived by the antenna elements 806 a-806 d is a direction D that formsa predetermined angle Θ(Θ=cos⁻¹(Φ/d)) with respect to the direction ofthe row of the antenna elements 806 a-806 d. It is assumed here thatreference numerals w1 to w3 in FIG. 10( a) denote planes of the receivedwaves in the same phase, respectively.

However, in the conventional phased-array antenna 803 having theabove-mentioned construction, the numbers of phase shifters 807 whichare located between the respective antenna elements 806 and the inputterminal 808 are different, and further, there are transmission lossesin the respective phase shifters 807. Therefore, the effects ofcombining powers from the respective antenna elements 806 a-806 d aredecreased, so that the shape of the beam that is shown in FIG. 10( b) isdeformed, whereby it is difficult to obtain a pointed beam (largedirectivity gain). In addition, the amount of beam tilt is reduced, andas a result, the control of the antenna's directivity is deteriorated.

Further, as described with reference to FIG. 9( a), each of the phaseshifters 807 that are used for the conventional phased-array antenna 830is formed in one piece, by allocating areas on the same plane to theferroelectric base material 702 and the paraelectric base material 701which constitute the phase shifter 700, respectively. Therefore, adistributed capacitance Cn per unit length of the line for themicrostrip hybrid coupler 703 and a distributed capacitance Cf per unitlength of the line for the microstrip stub 704 are greatly differentfrom each other. Accordingly, high-frequency power reflection isproduced at the connection between the microstrip hybrid coupler 703 andthe microstrip stub 704, whereby the power from the microstrip hybridcoupler 703 does not enter the microstrip stub 704 so efficiently, andconsequently, the sufficient phase shift amount cannot be obtained.

Hereinafter, a detailed explanation will be given. For, example, theline impedance Z is generally expressed by the distributed inductance Lper unit length of the line and the distributed capacitance C per unitlength of the line as Z^2 (the square of Z)=L/C. Further, when it isassumed that all fields exist only within the base material, and all ofthe fields are approximated to be linear and perpendicular to the groundconductor, the distributed capacitance C per unit length of the line isexpressed by the line width W, the base material thickness H, and thebase material permittivity ε, as C=εW/H. When the distributedcapacitance Cn per unit length of the line for the microstrip hybridcoupler 703 and the distributed capacitance Cf per unit length of theline for the microstrip stub 704 are compared with each other byutilizing the above-mentioned expressions, assuming that thepermittivity of the paraelectric base material 701 as the base materialof the microstrip hybrid coupler 703 is εn and the permittivity of theferroelectric base material 702 as the base material of the microstripstub 704 is εf, the relationship εn<<εf is generally established.Further, since the line widths W of the microstrip hybrid coupler 703and the microstrip stub 704, and the distances H of the respectiveconductors are the same, the distributed capacitance Cn per unit lengthof the line for the microstrip hybrid coupler 703 (=εnW/H) and thedistributed capacitance Cf per unit length of the line for themicrostrip stub 704 (=εfW/H) are greatly different. Consequently, asmentioned above, the power from the microstrip hybrid coupler 703 doesnot enter the microstrip stub 704 so efficiently, and thus, thesufficient phase shift amount cannot be obtained.

To overcome this problem, the method in which a magnetic material isprovided in proximity of the microstrip stub 704 to increase thedistributed inductance L per unit length of the line for the microstripstub 704, thereby enhancing the line impedance Z, is disclosed in theabove-mentioned Prior Art 1, and its construction is also suggestedtherein.

However, when the magnetic material is provided in proximity of themicrostrip stub 704 of the phase shifter 700 to suppress the reductionin the matching degree of the line impedance Z between both the linesections 703 and 704, so as to obtain a larger phase shift amount, as inthe above-mentioned Prior Art 1, there arises an additional problem inthat more processes are needed when the phase shifter 700 is produced byfiring. As a result, the manufacturing cost of the phase shifter isadversely increased.

The present invention is made to solve the above-mentioned problems.Accordingly, an object of the present invention is to provide an antennacontrol unit that can be manufactured in fewer manufacturing processes(low cost), and has a pointed beam (large directivity gain) and a largeamount of beam tilt, and a phased-array antenna that employs such anantenna control unit.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is providedan antenna control unit including plural antenna terminals to whichantenna elements are connected, a feeding terminal to which ahigh-frequency power is applied, and phase shifters which are connectedto the respective antenna terminals by feeding lines that branch offfrom the feeding terminal and electrically change a phase of ahigh-frequency signal that passes through between the respective antennaterminals and the feeding terminal. The phase shifters are placed atsome positions on the respective feeding lines, and the phase shiftersinclude a hybrid coupler on a paraelectric transmission line layer thatemploys a paraelectric material as a base material, and a stub on aferroelectric transmission line layer that employs a ferroelectricmaterial as a base material. The paraelectric transmission line layerand the ferroelectric transmission line layer are laminated through aground conductor, and the hybrid coupler and the stub are connected viaa through hole that passes through the ground conductor. Further, adistance between conductors that form a transmission line on theferroelectric transmission line layer is larger than a distance betweenconductors that form a transmission line on the paraelectrictransmission line layer.

Therefore, it is possible to obtain a low-cost phase shifter whichprovides an effective phase shift amount and is manufactured in fewprocesses. Consequently, an antenna control unit can be manufactured infew processes, whereby the manufacturing cost of the antenna controlunit can be reduced.

According to a second aspect of the present invention, there is providedan antenna control unit including plural antenna terminals to whichantenna elements are connected, a feeding terminal to which ahigh-frequency power is applied, and phase shifters which are connectedto the respective antenna terminals by feeding lines that branch offfrom the feeding terminal and electrically change a phase of ahigh-frequency signal that passes through between the respective antennaterminals and the feeding terminal. The phase shifters are placed atsome positions on the respective feeding lines, and the phase shiftersinclude a hybrid coupler on a paraelectric transmission line layer thatemploys a paraelectric material as a base material, and a stub on aferroelectric transmission line layer that employs a ferroelectricmaterial as a base material. The paraelectric transmission line layerand the ferroelectric transmission line layer are laminated through aground conductor, and the hybrid coupler and the stub areelectromagnetically connected via a coupling window that is formed onthe ground conductor. Further, a distance between conductors that form atransmission line on the ferroelectric transmission line layer is largerthan a distance between conductors that form a transmission line on aparaelectric transmission line layer.

Therefore, it is possible to obtain a lower-cost phase shifter thatprovides a more effective phase shift amount and is manufactured infewer processes. Consequently, an antenna control unit can bemanufactured in fewer processes, whereby the manufacturing cost of theantenna control unit can be reduced.

According to a third aspect of the present invention, there is provideda phased-array antenna that includes, on a dielectric substrate, pluralantenna elements, and an antenna control unit having a feeding terminalto which a high-frequency power is applied. Phase shifters that areconnected with the respective antenna elements by feeding lines whichbranch off from the feeding terminal and electrically change a phase ofa high-frequency signal that passes through between the respectiveantenna elements and the feeding terminal are also provided. The phaseshifters are placed at some positions on the feeding lines. The phaseshifters include a hybrid coupler on a paraelectric transmission linelayer that employs a paraelectric material as a base material, and astub on a ferroelectric transmission line layer that employs aferroelectric material as a base material. The paraelectric transmissionline layer and the ferroelectric transmission line layer are laminatedthrough a ground conductor, and the hybrid coupler and the stub areconnected via a through hole that passes through the ground conductor.Further, a distance between conductors that form a transmission line onthe ferroelectric transmission line layer is larger than a distancebetween conductors that form a transmission line on the paraelectrictransmission line layer.

Therefore, it is possible to obtain a low-cost phase shifter thatprovides an effective phase shift amount and is manufactured in fewprocesses. Consequently, a phased-array antenna can be manufactured infew processes, whereby the manufacturing cost of the phased-arrayantenna can be reduced.

According to a fourth aspect of the present invention, there is provideda phased-array antenna that includes, on a dielectric substrate, pluralantenna elements, and an antenna control unit having a feeding terminalto which a high-frequency power is applied. Phase shifters that areconnected with the respective antenna elements by feeding lines whichbranch off from the feeding terminal and electrically change a phase ofa high-frequency signal that passes through between the respectiveantenna elements and the feeding terminal are also provided. The phaseshifters are placed at some positions on the feeding lines. The phaseshifters include a hybrid coupler on a paraelectric transmission linelayer that employs a paraelectric material as a base material, and astub on a ferroelectric transmission line layer that employs aferroelectric material as a base material. The paraelectric transmissionline layer and the ferroelectric transmission line layer are laminatedthrough a ground conductor, and the hybrid coupler and the stub areelectromagnetically connected via a coupling window that is formed inthe ground conductor. Further, a distance between conductors that form atransmission line on the ferroelectric transmission line layer is largerthan a distance between conductors that form a transmission line on theparaelectric transmission line layer.

Therefore, it is possible to obtain a low-cost phase shifter thatprovides a more effective phase shift amount and is manufactured infewer manufacturing processes. Consequently, a phased-array antenna canbe manufactured in few processes, whereby the manufacturing cost of thephased-array antenna can be reduced.

According to a fifth aspect of the present invention, there is providedan antenna control unit including: a feeding terminal to which ahigh-frequency power is applied; a feeding line that branches off into mlines at a k-th branch stage from the feeding terminal when m=2^k (k-thpower of 2) (m, k is an integer); m antenna terminals for connectingantenna elements, which are provided on ends of the m feeding lines andarranged in a row, where the antenna terminals are referred to as first,second, . . . , and m-th antenna terminals, respectively; M_(k) phaseshifters (M_(k)=M_((k-1))×2+2^(k−1) when k≧1 and M₁=1) which all havethe same characteristics and electrically change a phase of ahigh-frequency signal that passes through the feeding line; and M_(k)loss elements which all have the same characteristics and have atransmission loss amount that is equal to a transmission loss amount ofthe phase shifter. The phase shifters are placed at some positions onthe feeding line that branch off into m lines, such that the number ofphase shifters which are located between a (n+1)-th antenna terminal (nis an integer that is from 1 to m−1) and the feeding terminal is onelarger than the number of phase shifters which are located between ann-th antenna terminal and the feeding terminal. The loss elements areplaced at some positions on the feeding line that branch off into mlines, such that the transmission loss amount from the n-th antennaterminal to the feeding terminal is larger than the transmission lossamount from the (n+1)-th antenna terminal to the feeding terminal, by atransmission loss amount corresponding to one phase shifter.

Therefore, variation in the amounts of distributed power to the mantenna terminals is avoided, whereby deformation of the beam shape orreduction in the amount of changes in the beam direction can be avoided.Consequently, an antenna control unit that has a pointed beam (largedirectivity gain) and a satisfactory beam tilt amount can be realized.

According to a sixth aspect of the present invention, there is providedan antenna control unit including: a feeding terminal to which ahigh-frequency power is applied; a feeding line that branches off into mlines at a k-th branch stage from the feeding terminal when m=2^k (k-thpower of 2) (m, k is an integer); m antenna terminals for connectingantenna elements, which are provided on ends of the m feeding lines andarranged in a row, where the antenna terminals are referred to as first,second, . . . , and m-th antenna terminals, respectively; M_(k) positivebeam tilting phase shifters (M_(k)=M_((k-1))×2+2^(k−1) when k≧1 andM₁=1) which all have the same characteristics and electrically change aphase of a high-frequency signal that passes through the feeding line ina positive direction; and M_(k) negative beam tilting phase shifterswhich all have the same characteristics and electrically change thephase of the high-frequency signal that passes through the feeding linein a negative direction. The positive beam tilting phase shifters areplaced at some positions on the feeding line that branch off into mlines, such that the number of the positive beam tilting phase shifterswhich are located between an (n+1)-th antenna terminal (n is an integerfrom 1 to m−1) and the feeding terminal is one larger than the number ofthe positive beam tilting phase shifters which are located between ann-th antenna terminal to the feeding terminal. The negative beam tiltingphase shifters are placed at some positions on the feeding line thatbranches off into m lines, such that the number of negative beam tiltingphase shifters which are located between an n-th antenna terminal to thefeeding terminal is one larger than the number of negative beam tiltingphase shifters which are located between an (n+1)-th antenna terminal tothe feeding terminal.

Therefore, variation in the amounts of distributed power to the mantenna terminals is avoided, whereby deformation of the beam shape orreduction in the amount of changes in the beam direction can be avoided,and further, the reduction in the beam tilt amount can be avoided evenwhen the phase shift amount of the phase shifter is small. Consequently,an antenna control unit that has a more pointed beam (larger directivitygain) and a more satisfactory beam tilt amount can be realized.

According to a seventh aspect of the present invention, there isprovided a two-dimensional antenna control unit including m₂ row antennacontrol units and one column antenna control unit. The row antennacontrol units are the antenna control unit according to the fifth aspectincluding m=m₁ antenna terminals (m₁ is an integer). The column antennacontrol unit is the antenna control unit according to the fifth aspectincluding m=m₂ antenna terminals (m₂ is an integer). The feedingterminals of the m₂ row antenna control units are connected to the m₂antenna terminals of the column antenna control unit, respectively.

Therefore, a two-dimensional antenna control unit that has a pointedbeam (large directivity gain) as well as a satisfactory beam tiltamount, and that can implement X-axial and Y-axial beam tilt can berealized.

According to an eighth aspect of the present invention, there isprovided a two-dimensional antenna control unit including m₂ row antennacontrol units and one column antenna control unit. The row antennacontrol units are the antenna control unit according to the sixth aspectincluding m=m₁ antenna terminals (m₁ is an integer). The column antennacontrol unit is the antenna control unit according to the sixth aspectincluding m=m₂ antenna terminals (m₂ is an integer). The feedingterminals of the m₂ row antenna control units are connected to the m₂antenna terminals of the column antenna control unit, respectively.

Therefore, a two-dimensional antenna control unit that has a morepointed beam (larger directivity gain) and a more satisfactory beamtilt, and that can implement the X-axial and Y-axial beam tilt can berealized.

According to a ninth aspect of the present invention, in accordance withthe phased-array antenna of the third aspect, the antenna control unitis the antenna control unit according to the fifth or sixth aspect.

Therefore, a two-dimensional antenna control unit that has a pointedbeam (large directivity gain) as well as a satisfactory beam tilt amountcan be manufactured in few processes, +thereby reducing themanufacturing cost.

According to a tenth aspect of the present invention, in accordance withthe phased-array antenna of the third aspect, the antenna control unitis the antenna control unit according to the seventh or eighth aspect.

Therefore, a phased-array antenna that has a pointed beam (largedirectivity gain) as well as a satisfactory beam tilt amount, and thatcan implement X-axial and Y-axial beam tilt can be manufactured in fewprocesses, thereby reducing the manufacturing cost.

According to an eleventh aspect of the present invention, in accordancewith the phased-array antenna of the fourth aspect, the antenna controlunit is the antenna control unit according to the fifth or sixth aspect.

There fore, a phased-array antenna that has a more pointed beam (largerdirectivity gain) as well as a more satisfactory beam tilt amount can bemanufactured in few processes, thereby reducing the manufacturing cost.

According to a twelfth aspect of the present invention, in accordancewith the phased-array antenna of the fourth aspect, the antenna controlunit is the antenna control unit according to the seventh or eighthaspect.

Therefore, a phased-array antenna that has a more pointed beam (largerdirectivity gain) as well as a more satisfactory beam tilt amount andthat can implement X-axial and Y-axial beam tilt can be manufactured infewer processes, thereby reducing the manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a perspective view FIG. 1( b) and is a cross-sectionalview illustrating a construction of a phase shifter according to a firstembodiment of the present invention, which is employed for aphased-array antenna.

FIG. 2( a) is a perspective view and FIG. 2( b is a cross-sectional viewillustrating a construction of a phase shifter according to a secondembodiment of the present invention, which is employed for aphased-array antenna.

FIG. 3( a) is a diagram illustrating a construction of a phased-arrayantenna according to a third embodiment of the present invention, andFIG. 3( b) is a diagram showing directivities of this phased-arrayantenna.

FIG. 4( a) is a diagram illustrating a construction of a phased-arrayantenna according to a fourth embodiment of the present invention, andFIG. 4( b) is a diagram showing directivities of this phased-arrayantenna.

FIG. 5 is a diagram illustrating a construction of a phased-arrayantenna according to a fifth embodiment of the present invention.

FIG. 6 is a diagram illustrating a construction of a phased-arrayantenna according to a sixth embodiment of the present invention.

FIG. 7 is a table showing the relationship of the number of branchstages (k), the number of antenna elements (m), and the number of phaseshifters (M_(k)) in the antenna control unit or phased-array antennaaccording to the sixth embodiment.

FIG. 8( a) is a diagram showing placements of phase shifters when k=1and m=2, FIG. 8( b) is a diagram showing placements of phase shifterswhen k=2 and m=4, and FIG. 8( c) is a diagram showing placements ofphase shifters when k=3 and m=8.

FIG. 9( a) is a diagram illustrating a construction of a phase shifterthat is employed for a conventional phased-array antenna, and FIG. 9( b)is a diagram showing permittivity changing characteristics of aferroelectric material.

FIG. 10( a) is a diagram showing a construction and operating principlesof the conventional phased-array antenna, and FIG. 10( b) is a diagramshowing directivities of the conventional phased-array antenna.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

Hereinafter, a first embodiment of the present invention will bedescribed with reference to FIGS. 1( a) and 1(b).

In the first embodiment, a phase shifter that is employed for aphased-array antenna of the present invention will be described.

FIG. 1( a) is a perspective view and FIG. 1( b) is a cross-sectionalview illustrating a construction of the phase shifter according to thefirst embodiment, which is employed for the phased-array antenna of thepresent invention.

In FIGS. 1( a) and 1(b), reference numeral 100 denotes a phase shifter.Reference numeral 101 denotes a paraelectric base material, referencenumeral 102 denotes a paraelectric transmission line layer, referencenumeral 103 denotes a microstrip hybrid coupler, reference numeral 104denotes a ferroelectric base material, reference numeral 105 denotes aferroelectric transmission line layer, reference numeral 106 denotes amicrostrip stub, reference numeral 107 denotes a ground conductor, andreference numeral 108 denotes a through hole by which the microstriphybrid coupler 103 and the microstrip stub 106 are connected through theground conductor 107.

Initially, a feature of the phase shifter 100 according to the firstembodiment, which is superior to the conventional phase shifter 700,will be described in detail.

As mentioned above, in the phase shifter 700 shown in FIG. 9( a), thedistributed capacitance Cn per unit length of the line for themicrostrip hybrid coupler 703 and the distributed capacitance Cf perunit length of the line for the microstrip stub 704 are greatlydifferent. As a result the power from the microstrip hybrid coupler 703does not enter the microstrip stub 704 so efficiently, whereby asufficient phase shift amount cannot be obtained. To overcome thisproblem, when a magnetic material is added to the microstrip stub 704 ofthe phase shifter 700 to increase the distributed inductance L per unitlength of the line as shown in Prior Art 1, the construction of theconventional phase shifter 700 that is formed in one piece by allocatingareas on the same plane to the ferroelectric base material 702 and theparaelectric base material 701, respectively, requires much moreprocesses, whereby the manufacturing cost is adversely increased.

Thus, in the phase shifter 100 of the first embodiment, as shown in FIG.1( a), the microstrip hybrid coupler 103 is formed on the paraelectrictransmission line layer 102 that employs a paraelectric material for thebase material 101, the microstrip stub 106 is formed on theferroelectric transmission line layer 105 that employs a ferroelectricmaterial for the base material 104, these two transmission line layers102 and 105 are laminated through the ground conductor 107, and then themicrostrip hybrid coupler 103 and the microstrip stub 106 are connectedvia through holes 108 which pass through the ground conductor 107.Further, as shown in FIG. 1( b), the distance Hf between conductors thatconstitute the transmission line of the ferroelectric transmission linelayer 105 is larger than the distance Hn between conductors thatconstitute the transmission line of the paraelectric transmission linelayer 102. Accordingly, the line impedances Z of the microstrip hybridcoupler 103 and the microstrip stub 106 can be matched, whereby thephase shifter 100 providing an effective phase shift amount can bemanufactured in simpler manufacturing processes.

A detailed explanation of the phase shifter will be given hereinafter.For example, assuming that the permittivity of the paraelectric basematerial 101 as the base material for the microstrip hybrid coupler 103is εn, and the permittivity of the ferroelectric base material 104 asthe base material for the microstrip stub 106 is εf, the distributedcapacitance Cn per unit length of the line for the microstrip hybridcoupler 103 is given by an expression Cn=εn·W/Hn, and the distributedcapacitance Cf per unit length of the line for the microstrip stub 106is given by an expression Cf=εf·W/Hf. When Cn and Cf are compared witheach other, the relationship εn<<εf is established as described above,but the relationship Hn<Hf is established as shown in FIG. 1( b), sothat the difference between the distributed capacitance Cn per unitlength of the line for the microstrip hybrid coupler 103 and thedistributed capacitance Cf per unit length of the line for themicrostrip stub 106 becomes smaller. Consequently, the reduction in thematching degree between the line impedances Z of the microstrip hybridcoupler 103 and the microstrip stub 106 can be avoided, so that thepower from the microstrip hybrid coupler 103 enters the microstrip stub106 efficiently, whereby a sufficient phase shift amount can beobtained.

Hereinafter, the operating principles of the phase shifter according tothe first embodiment will be described.

In the phase shifter 100, the microstrip hybrid coupler 103 using theparaelectric base material 101, the ground conductor 107, and themicrostrip stub 106 using the ferroelectric base material 104 arelaminated, and the microstrip hybrid coupler 103 and the microstrip stub106 are connected via through holes 108 that pass through the groundconductor 107. This phase shifter 100 is constituted such that the phaseshift amount of a high-frequency power that passes through themicrostrip hybrid coupler 103 varies according to a DC control voltagethat is applied to the microstrip stub 106.

In other words, the base material of the phase shifter 100 is composedof the paraelectric base material 101, the ground conductor 107, and theferroelectric base material 104. A rectangular loop-shaped conductorlayer 103 a is disposed on the paraelectric base material 101, and thisloop-shaped conductor layer 103 a and the paraelectric base material 101form the microstrip hybrid coupler 103.

Two linear conductor layers 106 a 1 and 106 a 2 are placed under theferroelectric base material 104 so as to be linked to one end of the twoopposed linear portions 103 a 1 and 103 a 2 of the rectangularloop-shaped conductor layer 103 a via the through holes 108,respectively. These two linear conductor layers 106 a 1 and 106 a 2 andthe ferroelectric base material 104 form the microstrip stub 106.

Conductor layers 115 a and 120 a are disposed on the paraelectric basematerial 101 so as to be located on extension lines of the two linearportions 103 a 1 and 103 a 2, and linked to the other ends of the twolinear portions 103 a 1 and 103 a 2, respectively.

This conductor layer 115 a and the paraelectric base material 101 forman input line 115, and the conductor layer 120 a and the paraelectricbase material 101 form an output line 120. Here, the one end and theother end of the linear portion 103 a 1 of the loop-shaped conductorlayer 103 a are ports 2 and 1 of the microstrip hybrid coupler 103,respectively, and the one end and the other end of the linear portion103 a 2 of the loop-shaped conductor layer 103 a are ports 3 and 4 ofthe microstrip hybrid coupler 103, respectively.

In the phase shifter 100 having the above-mentioned construction, when aDC control voltage is applied to the microstrip stub 106, the amount ofphase shift of a high-frequency power that passes therethrough varies.

Hereinafter, a detailed explanation of the phase shifter 100 will begiven. In the phase shifter 100 having a construction such that the samereflection element (microstrip stub 106) is connected to two adjacentports (ports 2 and 3) of the properly-designed microstrip hybrid coupler103 via the through holes 108, a high-frequency power that has enteredfrom the input port (port 1) is not outputted through this input port 1,but a high-frequency power on which a reflected power from thereflection element has been reflected is outputted only through theoutput port (port 4). Then, a bias field is produced when the controlvoltage is applied to the microstrip stub 106, and an effectivepermittivity of the microstrip stub 106 for the high-frequency powervaries when the control voltage is changed. Accordingly, an equivalentpower length of the microstrip stub 106 for the high-frequency powervaries, and the phase of the microstrip stub 106 varies according tochanges in the equivalent power length, whereby the phase of ahigh-frequency power that is outputted through the output port (port 4)varies.

As described above, the phase shifter 100 according to the firstembodiment is constituted by laminating planar sheet-type materials,i.e., the paraelectric base material 101, the ground conductor 107 andthe ferroelectric base material 104, and forming the through holes 108that pass through the ground conductor 107, whereby the microstriphybrid coupler 103 that is formed on the paraelectric transmission linelayer 102 and the microstrip stub 106 that is formed on theferroelectric transmission line layer 105 are connected each other.Furthermore, in this phase shifter 100, the thickness Hf of the basematerial of the ferroelectric transmission line layer 105 that isprovided with the microstrip stub 106 is larger than the thickness Hn ofthe base material of the paraelectric transmission line layer 102 thatis provided with the microstrip hybrid coupler 103. Therefore, thedeterioration in the line impedance matching between the microstriphybrid coupler 103 and the microstrip stub 106 is suppressed, whereby aphase shifter that provides an effective phase shift amount can beobtained. Further, this phase shifter 100 can be manufactured in fewermanufacturing processes as compared to the method by which the basematerials are disposed with allocating areas on the same plane to therespective base materials, as in the conventional phase shifter 700, andthus, the phase shifter 100 can be produced at a lower cost.

Further, when this phase shifter 100 is employed for a phased-arrayantenna, the phased-array antenna can be manufactured in fewerprocesses, thereby reducing the manufacturing cost.

Second Embodiment

A second embodiment of the present invention will be described withreference to FIGS. 2( a) and 2(b).

In this second embodiment, a phase shifter that is employed for aphased-array antenna of the present invention will be described.

FIG. 2( a) is a perspective view and FIG. 2( b) is a cross-sectionalview illustrating a construction of the phase shifter according to thesecond embodiment, which is employed for the phased-array antenna of thepresent invention.

In FIGS. 2( a) and 2(b), reference numeral 200 denotes a phase shifter.Reference numeral 201 denotes a paraelectric base material, referencenumeral 202 denotes a paraelectric transmission line layer, referencenumeral 203 denotes a microstrip hybrid coupler, reference numeral 204denotes a ferroelectric base material, reference numeral 205 denotes aferroelectric transmission line layer, reference numeral 206 denotes amicrostrip stub, reference numeral 207 denotes a ground conductor, andreference numeral 208 denotes a coupling window that is formed in theground conductor 207, for electromagnetically coupling the microstriphybrid coupler 203 and the microstrip stub 206.

Initially, a feature of the phase shifter 200 according to the secondembodiment, which is superior to the conventional phase shifter 700,will be described in detail.

As described in the first embodiment, when a magnetic material is addedto the microstrip stub 704 of the conventional phase shifter 700 shownin FIG. 9( a) to increase the distributed inductance L per unit lengthof the line as shown in Prior Art 1, so as to solve the problem that asufficient amount of phase shift for the conventional phase shifter 700is not obtained, the conventional phase shifter 700 that is formed inone piece by allocating areas on the same plane to the ferroelectricbase material 702 and the paraelectric base material 701, respectively,needs much more processes, whereby the manufacturing cost is increased.

In the phase shifter 200 according to the second embodiment as shown inFIG. 2( a), the microstrip hybrid coupler 203 is formed on theparaelectric transmission line layer 202 that uses a paraelectricmaterial for the base material 201, and the microstrip stub 206 isformed on the ferroelectric transmission line layer 205 that uses aferroelectric material for the base material 204. In addition, these twotransmission line layers 202 and 205 are then laminated through theground conductor 207, and the microstrip hybrid coupler 203 and themicrostrip stub 206 are electromagnetically connected via the couplingwindow 208 that is formed in the ground conductor 207. further, as shownin FIG. 2( b), the distance Hf between conductors that form thetransmission line on the ferroelectric transmission line layer 205 islarger than the distance Hn between conductors that form thetransmission line on the paraelectric transmission line layer 202.Accordingly, the line impedances Z of the microstrip hybrid coupler 203and the microstrip stub 206 can be matched, whereby the phase shifter200 providing an effective phase shift amount can be manufactured insimpler manufacturing processes.

Hereinafter, a detailed explanation of the phase shifter 200 will begiven. For example, assuming that the permittivity of the paraelectricbase material 201 as the base material of the microstrip hybrid coupler203 is εn and the permittivity of the ferroelectric base material 204 asthe base material of the microstrip stub 206 is εf, the distributedcapacitance Cn per unit length of the line for the microstrip hybridcoupler 203 is given by an expression Cn=εn·W/Hn, and the distributedcapacitance Cf per unit length of the line for the microstrip stub 206is given by an expression Cf=εf·W/Hf. When Cn and Cf are compared witheach other, the relationship εn<<εf is established, but in this secondembodiment, the relationship of Hn<Hf is established as shown in FIG. 2(b). Accordingly, the difference between the distributed capacitance Cnper unit length of the line for the microstrip hybrid coupler 203 andthe distributed capacitance Cf per unit length of the line for themicrostrip stub 206 becomes smaller. Consequently, the deterioration ofthe matching between the line impedances Z of the microstrip hybridcoupler 203 and the microstrip stub 206 can be avoided, whereby thepower from the microstrip hybrid coupler 203 enters the microstrip stub206 efficiently, and a sufficient phase shift amount can be obtained.

Hereinafter, the operating principles of the phase shifter 200 accordingto the second embodiment will be described.

In this phase shifter 200, the microstrip hybrid coupler 203 using theparaelectric base material 201, the ground conductor 207, and themicrostrip stub 206 using the ferroelectric base material 204 arelaminated, and the microstrip hybrid coupler 203 and the microstrip stub206 are electromagnetically connected via the coupling window 208 thatis formed in the ground conductor 207. This phase shifter 200 isconstituted so that the amount of phase shift of the high-frequencypower that passes through the microstrip hybrid coupler 203 variesaccording to a DC control voltage that is applied to the microstrip stub206.

In other words, the base material of the phase shifter 200 is composedof the paraelectric base material 201, the ground conductor 207, and theferroelectric base material 204. A rectangular loop-shaped conductorlayer 203 a is disposed on the paraelectric base material 201, and thisloop-shaped conductor layer 203 a and the paraelectric base material 201form the microstrip hybrid coupler 203.

Two linear conductor layers 206 a 1 and 206 a 2 are disposed under theferroelectric base material 204 so as to be electromagneticallyconnected to one end of the two opposed linear portions 203 a 1 and 203a 2 of the rectangular loop-shaped conductor layer 203 a, respectively,via the coupling window 208. These two linear conductor layers 206 a 1and 206 a 2 and the ferroelectric base material 204 form the microstripstub 206.

Further, conductor layers 215 a and 220 a are disposed on theparaelectric base material 201 so as to be located on extension lines ofthe two linear portions 203 a 1 and 203 a 2 and linked to the other endsof the two linear portions 203 a 1 and 203 a 2, respectively.

This conductor layer 215 a and the paraelectric base material 201 forman input line 215, and the conductor layer 220 a and the paraelectricbase material 201 form an output line 220. Here, the one end and theother end of the linear portion 203 a 1 of the loop-shaped conductorlayer 203 a are ports 2 and 1 of the microstrip hybrid coupler 203,respectively, and the one end and the other end of the linear portion203 a 2 of the loop-shaped conductor layer 203 a are ports 3 and 4 ofthe microstrip hybrid coupler 203, respectively.

In the phase shifter 200 having the above-mentioned construction, when aDC control voltage is applied to the microstrip stub 206, the amount ofphase shift of the high-frequency power that passes therethrough varies.

Hereinafter, a detailed explanation of the phase shifter 200 will begiven. In the phase shifter 200 in which the same reflection element(microstrip stub 206) is electromagnetically connected to two adjacentports (ports 2 and 3) of the properly-designed microstrip hybrid coupler203 via the coupling window 208, a high-frequency power that has enteredfrom the input port (port 1) is not outputted from this input port 1,and a high-frequency power upon which a reflected power from thereflection element has been reflected is outputted only through theoutput port (port 4). Then, a bias field is produced when a controlvoltage is applied to the microstrip stub 206, and the effectivepermittivity of the microstrip stub 206 for the high-frequency powervaries when this control voltage is changed. Accordingly, the equivalentelectrical length of the microstrip stub 206 for the high-frequencypower varies, whereby the phase of the high-frequency power that isoutputted from the output port (port 4) varies.

As described above, according to the second embodiment, the phaseshifter 200 is constituted by laminating planar sheet-type materials,i.e., the paraelectric base material 201, the ground conductor 207comprising the coupling window 208, and the ferroelectric base material204, in which the thickness Hf of the base material for theferroelectric transmission line layer 205 that is provided with themicrostrip stub 206 is larger than the thickness Hn of the base materialfor the paraelectric transmission line layer 202 that is provided withthe microstrip hybrid coupler 203. Therefore, the deterioration of theline impedance matching between the microstrip hybrid coupler 203 andthe microstrip stub 206 can be avoided, whereby a phase shifterproviding an effective phase shift amount can be obtained. Further, thisphase shifter 200 can be manufactured in fewer manufacturing processesas compared to the method by which the base materials are disposed suchthat areas on one plane are allocated to the respective base materials,as in the conventional phase shifter 700, whereby the phase shifter canbe produced with a lower cost.

Further, when the phase shifter 200 is employed for a phased-arrayantenna, the phased-array antenna can be manufactured in fewerprocesses, thereby reducing the manufacturing cost.

Third Embodiment

A third embodiment of the present invention will be described withreference to FIGS. 3( a) and 3(b).

FIG. 3( a) is a diagram illustrating a construction of a phased-arrayantenna according to the third embodiment, and FIG. 3( b) is a diagramshowing directivities of the phased-array antenna according to the thirdembodiment in a case where a beam tilt voltage is applied and a casewhere a beam tilt voltage is not applied.

In FIG. 3( a), a phased-array antenna 330 according to the thirdembodiment comprises an antenna control unit 300, a beam tilt voltage320 for performing control of the directivity (beam tilt) as shown inFIG. 3( b), and four antenna elements 310 a-310 d. The antenna controlunit 300 comprises an input terminal (feeding terminal) 301, fourantenna terminals 307 a-307 d, four phase shifters 308 a 1-308 a 4, fourloss elements 309 a 1-309 a 4, a high frequency blocking element 311, aDC blocking element 312, a transmission line (feeding line) 302 from theinput terminal 301, two transmission lines 304 a and 304 b that branchoff at a first branch 303, and four transmission lines 306 a-306 d thatbranch off from the transmission lines 304 a and 304 b at secondbranches 305 a and 305 b.

Hereinafter, the construction of the antenna control unit 300 thatconstitutes the phased-array antenna 330 according to the thirdembodiment will be described in more detail.

The antenna control unit 300 according to the third embodiment includesone input terminal 301, the transmission line 302 from the inputterminal 301 then branches off into two transmission lines 304 a and 304b at the first branch 303, and further, the two transmission lines 304 aand 304 b that branch off at the first branch 303 further branch offinto two transmission lines at the second branches 305 a and 305 b,whereby four branched transmission lines 306 a-306 d are obtained.

Further, the input terminal 301 is connected to the first branch 303through the blocking element 312, and the beam tilt voltage 320 isconnected to the first branch 303 through the high frequency blockingelement 311.

The four transmission lines 306 a-306 d are provided with four antennaterminals 307 a-307 d for connection with the four antenna elements 310a-310 d.

When the four antenna terminals 307 a-307 d are arranged in a row, whichare referred to as first, second, third, and fourth antenna terminals,respectively, and when it is assumed that n is an integer that satisfies0<n<4, the phase shifters 308 a 1-308 a 4 are arranged so that thenumber of phase shifters 308 a which are located between the (n+1)-thantenna terminal 307 and the input terminal 301 is one larger than thenumber of phase shifters 308 a which are located between the n-thantenna terminal 307 and the input terminal 301. Here, the respectivephase shifters 308 a 1-308 a 4 have the same characteristics.

Further, in the antenna control unit 300 according to the thirdembodiment, the loss elements 309 a 1-309 a 4 each having a transmissionloss that is equal to a transmission loss amount corresponding to onephase shifter 308 a are placed so that the number of loss elements 309 awhich are located between the n-th antenna terminal 307 and the inputterminal 301 is one larger than the number of loss elements 309 a whichare located between the (n+1)-th antenna terminal 307 and the inputterminal 301. Therefore, the transmission loss amounts from all theantenna terminals 307 a-307 d to the input terminal 301 are of the samevalue.

In common phased-array antennas, when the transmission loss amounts fromthe respective antenna elements 310 a-310 d to the input terminal 301 asa power composition point are different from each other, the powercompositing effect is reduced, whereby the shape of the beam as shown inFIG. 3( b) is deformed and it becomes difficult to obtain a pointed beam(large directivity gain), and the beam tilt amount is reduced. As aresult, the control of the antenna's directivity is deteriorated.

However, in the antenna control unit 300 according to the thirdembodiment, the loss elements 309 a are placed so that the amount oftransmission loss which occurs from then-th antenna terminal 307 (n isan integer that satisfies 0<n<4) to the input terminal 301 is largerthan the transmission loss amount from the (n+1)-th antenna terminal 307to the input terminal 301, by an amount as much as the transmission losscorresponding to one phase shifter 308 a. Therefore, the transmissionloss amounts from all the antenna elements 310 a-310 d to the inputterminal 301 are of the same value, whereby a phased-array antenna thathas a pointed beam and a satisfactory beam tilt amount can be realized.

As described above, according to the third embodiment, when n is aninteger that satisfies 0<n<4, the phase shifters 308 a are placed suchthat the number of phase shifters 308 a which are located between the(n+1)-th antenna terminal 307 and the input terminal 301 is one largerthan the number of phase shifters 308 a which are located between then-th antenna terminal 307 and the input terminal 301. Further, the losselements 309 a are placed such that the transmission loss amount fromthe n-th antenna terminal 307 to the input terminal 301 is larger thanthe transmission loss amount from the (n+1)-th antenna terminal 307 tothe input terminal 301, by an amount as much as the transmission losscorresponding to one phase shifter 308 a. Therefore, even when anypassage loss is generated in the phase shifters 308 a 1-308 a 4, theamounts of distributed power for the respective antenna elements 310a-310 d are not different from each other. Consequently, the antennacontrol unit 300 by which the beam shape is not deformed or the changesin the beam direction are not reduced can be obtained. Further, whenthis antenna control unit 300 is employed for a phased-array antenna,the transmission loss amounts from all of the antenna elements 310 a-310d to the input terminal 301 can be made equal, whereby a phased-arrayantenna that has a pointed beam and a satisfactory beam tilt amount canbe realized.

Further, when the phase shifter as described in the first or secondembodiment is employed for the phased-array antenna according to thethird embodiment, the manufacturing cost of the phased-array antenna canbe further reduced.

Fourth Embodiment

A fourth embodiment will be described with reference to FIGS. 4( a) and4(b).

In this fourth embodiment, an antenna control unit in a phased-arrayantenna, which has a different construction from that of the thirdembodiment, will be described in detail.

FIG. 4( a) is a diagram illustrating a construction of a phased-arrayantenna according to the fourth embodiment, and FIG. 4( b) is a diagramshowing directivities of the phased-array antenna according to thefourth embodiment in a case where a beam tilt voltage is applied and acase where the beam tilt voltage is not applied.

In FIG. 4( a), a phased-array antenna 430 according to the fourthembodiment comprises an antenna control unit 400, negative and positivebeam tilt voltages 421 and 422 that perform control on negative andpositive directivities (beam tilt), respectively, as shown in FIG. 4(b), and four antenna elements 410 a-410 d. The antenna control unit 400comprises an input terminal 401, four antenna terminals 407 a-407 d,four positive beam tilting phase shifters 408 a 1-408 a 4, four negativebeam tilting phase shifters 408 b 1-408 b 4, high frequency blockingelements 411 a-411 f, DC blocking elements 412 a-412 f, a transmissionline 402 from the input terminal 401, two transmission lines 404 a and404 b that branch off at a first branch 403, and four transmission lines406 a-406 d that branch off from the transmission lines 404 a and 404 bat second branches 405 a and 405 b.

Hereinafter, the antenna control unit 400 that constitutes thephased-array antenna 430 according to the fourth embodiment will bedescribed in more detail.

The antenna control unit 400 of the fourth embodiment includes one inputterminal 401, and the transmission line 402 from the input terminal 401then branches off into the two transmission lines 404 a and 404 b at thefirst branch 403. Further, the two transmission lines 404 a and 404 bthat branch off at the first branch 403 branch off into two transmissionlines at the second branches 405 a and 405 b, respectively, therebyresulting in four transmission lines 406 a-406 d.

Each of the two transmission lines 404 a and 404 b that branch off atthe first branch 403 is provided with one DC blocking element 412, andfurther, each of the four transmission lines 406 a-406 d that branch offat the second branches 405 a and 405 b, respectively, is provided withone DC blocking element 412. A high frequency block element 411 isplaced on one end of the respective negative beam tilting phase shifters408 b 1, 408 b 4, and, 408 b 2, and on one end of the respectivepositive beam tilting phase shifters 408 a 1, 408 a 4, and 408 a 2.

The four transmission lines 406 a-406 d are provided with four antennaterminals 407 a-407 d, respectively, so as to be connected to fourantenna elements 410 a-410 d.

These four antenna terminals 407 a-407 d, which are referred to asfirst, second, third, and fourth antenna terminals, respectively, arearranged in a row, and when assuming that n is an integer that satisfies0<n<4, the positive beam tilting phase shifters 408 a 1-408 a 4 areplaced so that the number of phase shifters which are located from the(n+1)-th antenna terminal 407 to the input terminal 401 is one largerthan the number of phase shifters which are located from the n-thantenna terminal 407 to the input terminal 401.

Further, the negative beam tilting phase shifters 408 b 1-408 b 4 areplaced so that the number of phase shifters which are located betweenthe n-th antenna terminal 407 and the input terminal 401 is one largerthan the number of phase shifters which are located between the (n+1)-thantenna terminal 407 and the input terminal 401.

Here, the positive beam tilting phase shifters 408 a 1-408 a 4 andnegative beam tilting phase shifters 408 b 1-408 b 4 all have the samecharacteristics (same transmission loss amount).

Therefore, in the antenna control unit 400 having the above-mentionedconstruction, the transmission loss amounts from all the antennaterminals 407 a-407 d to the input terminal 401 are the same.

In common phased-array antennas, when the transmission loss amounts fromthe respective antenna elements 410 a-410 d to the input terminal 401 asthe electric power composition point are different from each other, theelectric power composition effect is reduced, whereby the shape of beamas shown in FIG. 4( b) is deformed, and thus it is difficult to obtain apointed beam (large directivity gain), and the beam tilt amount isreduced. As a result, the control on the antenna's directivity isdeteriorated.

Further, in a phased-array antenna that uses the ferroelectric materialfor the phase shifter 408, when the rate of change in the permittivityof the ferroelectric material is small, a phase shift amount that can berealized by one phase shifter 408 is small, so that it is quitedifficult to obtain a phased-array antenna having a large amount of beamtilt.

However, in this antenna control unit 400 according to the fourthembodiment, the transmission loss amounts from all the antenna elements410 a-410 d to the input terminal 401 are the same, and further, thepositive beam tilting phase shifters 408 a and the negative beam tiltingphase shifters 408 b are provided. Therefore, each of the phase shifters408 takes charge of only a smaller phase shift amount, whereby aphased-array antenna having a more pointed beam and a more satisfactorybeam tilt amount can be realized.

As described above, according to the fourth embodiment, when n is aninteger that satisfies 0<n<4, the positive beam tilting phase shifters408 a 1-408 a 4 are placed so that the number of positive beam tiltingphase shifters 408 a which are located between the (n+1)-th antennaterminal 407 and the input terminal 401 is one larger than the number ofpositive beam tilting phase shifters 408 a which are located between then-th antenna terminal 407 and the input terminal 401. Further, thenegative beam tilting phase shifters 408 b 1-408 b 4 are placed so thatthe number of negative beam tilting phase shifters 408 b which arelocated between the n-th antenna terminal 407 and the input terminal 401is one larger than the number of negative beam tilting phase shifters408 b which are located between the (n+1)-th antenna terminal 407 andthe input terminal 401. Therefore, each of the phase shifters 408 takescharge of only a smaller phase shift amount, and consequently, anantenna control unit 400 which does not reduce the beam tilt amount evenwhen the permittivity change rate for the ferroelectric material of eachphase shifter 408 is low can be obtained. Further, when the antennacontrol unit 400 is employed, the transmission loss amounts from all theantenna elements 410 a-410 d to the input terminal 401 can be equalized,whereby a phased-array antenna that has a more pointed beam and a moresatisfactory beam tilt amount can be realized.

Further, when the phase shifter as described in the first or secondembodiment is employed for the phased-array antenna according to thefourth embodiment, the manufacturing cost of the phased-array antennacan be further reduced.

Fifth Embodiment

A fifth embodiment of the present invention will be described withreference to FIG. 5.

In this fifth embodiment, a description will be given of a phased-arrayantenna comprising a two-dimensional antenna control unit that isobtained by combining a plurality of the antenna control units that havebeen described in the third embodiment, and can control the directivityin the X-axis direction and the Y-axis direction.

FIG. 5 is a diagram illustrating a construction of a phased-arrayantenna according to the fifth embodiment.

In FIG. 5, a phased-array antenna 530 according to the fifth embodimentcomprises antenna elements 510 a(1-4)-510 d(1-4), X-axial antennacontrol units 500 a 1-500 a 4 that perform control of the X-axialdirectivity (beam tilt), a Y-axial antenna control unit 500 b thatperforms control of the Y-axial directivity, an X-axial beam tiltvoltage 520 a, and a Y-axial beam tilt voltage 520 b. Each of theX-axial antenna control units 500 a includes antenna terminals 507 a-507d, and an input terminal 501 a. The Y-axial antenna control unit 500 bincludes antenna terminals 507 a-507 d, and an input terminal 501 b.Here, it is assumed that each of the X-axial antenna control units 500 a1-500 a 4 and the Y-axial antenna control unit 500 b has the sameconstruction as that of the antenna control unit 300 as described abovein detail in the third embodiment.

Hereinafter, the phased-array antenna 530 according to this embodimentwill be specifically described.

The input terminals 501 a 1-501 a 4 of the X-axial antenna control units500 a 1-500 a 4 are connected to the antenna terminals 507 a-507 d ofthe Y-axial antenna control unit 500 b, respectively. Although not shownhere, four phase shifters 308 a and four loss elements 309 a each havingthe same transmission loss amount are disposed in each of the X-axialantenna control units 500 a 1-500 a 4 and the Y-axial antenna controlunit 500 b as shown in FIG. 3, as described in the third embodiment.

Therefore, according to the phased-array antenna 530 of the fifthembodiment, the transmission loss amounts from all the antenna terminals507 a-507 d to the input terminal 501 a in the X-axial antenna controlunits 500 a 1-500 a 4 are of the same value, and further, thetransmission loss amounts from all the antenna terminals 507 a-507 d tothe input terminal 501 b in the Y-axial antenna control unit 500 b areof the same value. Accordingly, a phased-array antenna that has apointed beam (large directivity gain) and a satisfactory beam tiltamount, and that can control the X-axial directivity and the Y-axialdirectivity can be realized.

As described above, the phased-array antenna of the fifth embodimentemploys an antenna control unit which includes the X-axial antennacontrol units 500 a 1-500 a 4 that control the X-axial directivity andthe Y-axial antenna control unit 500 b that controls the Y-axialdirectivity. Further, as the X-axial and Y-axial antenna control units500, an antenna control unit as described in the third embodiment, whichis provided with the phase shifters 308 a and the loss elements 309 awhich number as many as the phase shifters 308 a, is employed, whereeach loss element has the same transmission loss amount as the phaseshifter 308 a, whereby the distributed power to the respective antennaelements 510 is equalized also when any passage loss occurs in the phaseshifter 308, thereby to prevent the deformation of the beam shape or thereduction in the beam tilt changes. Therefore, a phased-array antennathat has a pointed beam (large directivity gain) and a satisfactory beamtilt amount, and that can control the X-axial and Y-axial directivitiescan be realized.

Sixth Embodiment

A sixth embodiment of the present invention will be described withreference to FIG. 6.

In this sixth embodiment, a phased-array antenna having atwo-dimensional antenna control unit which is obtained by combining aplurality of the antenna control units as described in the fourthembodiment and can control X-axial and Y-axial directivities will bedescribed.

FIG. 6 is a diagram illustrating a construction of a phased-arrayantenna according to the sixth embodiment.

In FIG. 6, a phased-array antenna 630 of the sixth embodiment includesantenna elements 610 a(1-4)-610 d(1-4), X-axial antenna control units600 a 1-600 a 4 that perform control of the X-axial directivity (beamtilt), a Y-axial antenna control unit 600 b that performs control of theY-axial directivity, an X-axial negative beam tilt voltage 621 a, anX-axial positive beam tilt voltage 622 a, a Y-axial negative beam tiltvoltage 621 b, and a Y-axial positive beam tilt voltage 622 b. Further,each of the X-axial antenna control units 600 a includes antennaterminals 607 a-607 d, and an input terminal 601 a. The Y-axial antennacontrol unit 600 b includes antenna terminals 607 a-607 d, and the inputterminal 601 b. It is assumed here that each of the X-axial antennacontrol units 600 a 1-600 a 4 and the Y-axial antenna control unit 600 bhas the same construction as that of the antenna control unit 400 thathas been specifically described in the fourth embodiment.

Hereinafter, the phased-array antenna 630 according to the sixthembodiment will be described in more detail.

The input terminals 601 a 1-601 a 4 of the X-axial antenna control units600 a 1-600 a 4 are connected to the antenna terminals 607 a-607 d ofthe Y-axial antenna control unit 600 b, respectively. Although not shownhere, four positive beam tilting phase shifters 408 a and four negativebeam tilting phase shifters 408 b are included in each of the X-axialantenna control units 600 a 1-600 a 4 and the Y-axial antenna controlunit 600 b, as shown in FIG. 4, as described in the fourth embodiment.

Therefore, according to the phased-array antenna 630 of the sixthembodiment, in each of the X-axial antenna control units 600 a 1-600 a 4and the Y-axial antenna control unit 600 b, the transmission lossamounts from all the antenna terminals 607 a-607 d to the input terminal601 a are of the same value, and each phase shifter takes charge of onlya smaller phase shift amount, whereby a phased-array antenna which has amore pointed beam and a more satisfactory beam tilt amount, and whichcan control the X-axial and Y-axial directivities can be realized.

As described above, according to the sixth embodiment, the phased-arrayantenna includes the X-axial antenna control units 600 a 1-600 a 4 thatcontrol the X-axial directivity, and the Y-axial antenna control unit600 b that controls the Y-axial directivity. Further, as the X-axial andY-axial antenna control units 600, an antenna control unit is employedin which equal numbers of positive beam tilting phase shifters 408 a andnegative beam tilting phase shifters 408 b each having the sametransmission loss amount are disposed as described in the fourthembodiment. Thus, each of the phase shifters 408 takes charge of only asmaller phase shift amount even when the permittivity change rate of theferroelectric material for each phase shifter 408 is low, therebyavoiding the reduction in the beam tilt amount. Further, the distributedpower to the respective antenna elements 610 are equalized even when thepassage loss arises in each phase shifter, whereby the deformation ofthe beam shape or the reduction of changes in the beam direction can beprevented. Therefore, a phased-array antenna which has a more pointedbeam and a more satisfactory beam tilt amount, and which can control theX-axial and Y-axial directivities can be realized.

Further, in each of the antenna control units 600 that constitute thephased-array antenna of the sixth embodiment, when the X-axial positivebeam tilting phase shifters, the X-axial negative beam tilting phaseshifters, the Y-axial positive beam tilting phase shifters, and theY-axial negative beam tilting phase shifters are disposed on differentlayers, a more high-density and compact antenna control unit can berealized in addition to the above-mentioned effects.

In the description of any of the above embodiments, the transmissionlines that constitute the microstrip hybrid coupler and the microstripstub of the phase shifter are of the microstrip line type. However, whenany type of a dielectric waveguide such as a strip line type, a H-linedielectric waveguide, or a NRD dielectric waveguide is employed, thesame effects as described above are also achieved.

Further, while four antenna elements are employed in any of theabove-mentioned embodiments, another number of antenna elements may beemployed. For example, when a feeding line (transmission line) branchesoff into m lines through k branch stages from an input terminal to whicha high-frequency power is applied (m=2^k (k-th power of 2), (k is aninteger)), only m pieces of antenna elements are required, and thenumber M_(k) of phase shifters that are then required can be given bythe following expression:M _(k) =M _((k-1))×2+2^(k−1) (when k≧=1, M₁=1)

Hereinafter, a detailed explanation will be given with reference toFIGS. 7 and 8. FIG. 7 is a diagram showing the relationship of thenumber of branch stages (k), the number of antenna elements (m), and thenumber of phase shifters (M_(k)) in the antenna control unit orphased-array antenna according to the sixth embodiment. FIG. 8( a) is adiagram showing an arrangement of phase shifters in a case where k=1 andm=2 in FIG. 7, FIG. 8( b) is a diagram showing an arrangement of phaseshifters in a case where k=2 and m=4, and FIG. 8( c) is a diagramshowing an arrangement of phase shifters in a case where k=3 and m=8.

For example, when the number of branch stages is k=3, the number m ofantenna elements is m=2^3=8 as shown in FIG. 7, and the number M₃ ofphase shifters is M₃=M₂×2+2^2=12. The phase shifters in this case arearranged as shown in FIG. 8( c) such that the number of phase shifterswhich are located between the (n+1)-th antenna terminal (0<n<8) and theinput terminal is one larger than the number of phase shifters which arelocated between the n-th antenna terminal and the input terminal. Forthe sake of simplifying the explanation, only M_(k) phase shifters areshown in FIG. 8, but in the antenna control unit 300 as described in thethird embodiment and the phased-array antenna 330 that employs thisantenna control unit 300, M_(k) loss elements which number as many asthe phase shifters are further disposed as shown in FIG. 3. In the caseof the antenna control unit 400 as described in the fourth embodimentand the phased-array antenna 430 that employs this antenna control unit400, when the M_(k) phase shifters shown in this figure are positivebeam tilting phase shifters, M_(k) negative beam tilting phase shiftersare further disposed as shown in FIG. 4.

INDUSTRIAL AVAILABILITY

The antenna control unit and the phased-array antenna according to thepresent invention are quite useful in realizing a low-cost antennacontrol unit and phased-array antenna that has a pointed beam (largedirectivity gain) and a satisfactory beam tilt amount, and that can bemanufactured in fewer manufacturing processes. The antenna control unitand the phased-array antenna are particularly suitable for use in mobileunit identifying radio, or automobile collision avoidance radar.

1. An antenna control unit including plural antenna terminals to which antenna elements are connected, a feeding terminal to which a high-frequency power is applied, and phase shifters which are connected to the respective antenna terminals by feeding lines that branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna terminals and the feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are connected via a through hole that passes through the ground conductor; and a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer.
 2. An antenna control unit including plural antenna terminals to which antenna elements are connected, a feeding terminal to which a high-frequency power is applied, and phase shifters which are connected to the respective antenna terminals by feeding lines that branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna terminals and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are electromagnetically connected via a coupling window that is formed on the ground conductor; and a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer.
 3. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are connected via a through hole that passes through the ground conductors; and a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer.
 4. The phased-array antenna of claim 3 wherein said antenna control unit includes: said feeding terminal to which the high-frequency power is applied; said feeding line that branches off into m pieces of lines at a k-th branch stage from said feeding terminal when m=2^(k), where m and k are integers; said m pieces of antenna terminals for connecting said antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; said M_(k) pieces of phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1, which all have the same characteristics and electrically change a phase of the high-frequency signal that passes through said feeding line; and M_(k) pieces of loss elements which all have the same characteristics and have a transmission loss amount that is equal to a transmission loss amount of one of said phase shifters, wherein: said phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said phase shifters which are located between a (n+1)-th antenna terminal, where n is an integer that is from 1 to m−1, and said feeding terminal is one larger than the number of said phase shifters which are located between an n-th antenna terminal and the feeding terminal; and said M_(k) loss elements are placed at some positions on said feeding line that branches off into m pieces of lines, such that the transmission loss amount from the n-th antenna terminal to said feeding terminal is larger than the transmission loss amount from the (n+1)-th antenna terminal to said feeding terminal, by a transmission loss amount corresponding to one of said phase shifters.
 5. The phased-array antenna of claim 3, wherein said antenna control unit includes: said feeding terminal to which the high-frequency power is applied; said feeding line that branches off into m pieces of lines at a k-th branch stage from the feeding terminal when m=2^(k), where m and k are integers; said m pieces of antenna terminals for connecting said antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; M_(k) pieces of positive beam tilting phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1) which all have the same characteristics and electrically change a phase of the high-frequency signal that passes through said feeding line in a positive direction; and M_(k) pieces of negative beam tilting phase shifters which all have the same characteristics and electrically change the phase of the high-frequency signal that passes through said feeding line in a negative direction, wherein: said positive beam tilting phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said positive beam tilting phase shifters which are located between an (n+1)-th antenna terminal, where n is an integer from 1 to m−1, and said feeding terminal is one larger than the number of said positive beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal; and said negative beam tilting phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said negative beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal is one larger than the number of said negative beam tilting phase shifters which are located between an (n+1)-th antenna terminal to said feeding terminal.
 6. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are electromagnetically connected via a coupling window that is formed in the ground conductor; and a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer.
 7. The phased-array antenna of claim 6, wherein said antenna control unit includes: said feeding terminal to which the high-frequency power is applied; said feeding line that branches off into m pieces of lines at a k-th branch stage from said feeding terminal when m=2^(k), where m and k are integers; said m pieces of antenna terminals for connecting antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; said M_(k) pieces of phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1, which all have the same characteristics and electrically change a phase of the high-frequency signal that passes through said feeding line; and M_(k) pieces of loss elements which all have the same characteristics and have a transmission loss amount that is equal to a transmission loss amount of one of said phase shifters, wherein: said phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said phase shifters which are located between a (n+1)-th antenna terminal, where n is an integer that is from 1 to m−1, and said feeding terminal is one larger than the number of said phase shifters which are located between an n-th antenna terminal and said feeding terminal; and said loss elements are placed at some positions on said feeding line that branches off into m pieces of lines, such that the transmission loss amount from the n-th antenna terminal to said feeding terminal is larger than the transmission loss amount from the (n+1)-th antenna terminal to said feeding terminal, by a transmission loss amount corresponding to one of said phase shifters.
 8. The phased-array antenna of claim 6, wherein said antenna control unit includes: said feeding terminal to which the high-frequency power is applied; said feeding line that branches off into m pieces of lines at a k-th branch stage from said feeding terminal when m=2^(k), where m and k are integers; said pieces of antenna terminals for connecting said antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; M_(k) pieces of positive beam tilting phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1, which all have the same characteristics and electrically change a phase of the high-frequency signal that passes through said feeding line in a positive direction; and M_(k) pieces of negative beam tilting phase shifters which all have the same characteristics and electrically change the phase of the high-frequency signal that passes through said feeding line in a negative direction, wherein: said positive beam tilting phase shifters are placed at some positions on the feeding line that branches off into m pieces of lines, such that the number of said positive beam tilting phase shifters which are located between an (n+1)-th antenna terminal, where n is an integer from 1 to m−1, and said feeding terminal is one larger than the number of said positive beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal; and said negative beam tilting phase shifters are placed at some positions on said feeding lines that branches off into m pieces of lines, such that the number of said negative beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal is one larger than the number of said negative beam tilting phase shifters which are located between an (n+1)-th antenna terminal to said feeding terminal.
 9. An antenna control unit including: a feeding terminal to which a high-frequency power is applied; a feeding line that branches off into m pieces of lines at a k-th branch stage from said feeding terminal when m=2^(k), where m and k are integers; m pieces of antenna terminals for connecting antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; M_(k) pieces of phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1, which all have the same characteristics and electrically change a phase of a high-frequency signal that passes through said feeding line; and M_(k) pieces of loss elements which all have the same characteristics and have a transmission loss amount that is equal to a transmission loss amount of one of said phase shifters, wherein: said phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said phase shifters which are located between a (n+1)-th antenna terminal, where n is an integer that is from 1 to m−1, and said feeding terminal is one larger than the number of said phase shifters which are located between an n-th antenna terminal and said feeding terminal; and said loss elements are placed at some positions on said feeding line that branches off into m pieces of lines, such that the transmission loss amount from the n-th antenna terminal to said feeding terminal is larger than the transmission loss amount from the (n+1)-th antenna terminal to said feeding terminal, by a transmission loss amount corresponding to one of said phase shifters.
 10. A two-dimensional antenna control unit including: m₂ pieces of row antenna control units and one column antenna control unit, wherein: said m₂ pieces of row antenna controls unit are said antenna control unit of claim 9 including m=m₁ pieces of antenna terminals, where m₁ is an integer; said column antenna control unit is said antenna control unit of claim 9 including m=m₂ pieces of antenna terminals, where m₂ is an integer; and said feeding terminals of said m₂ pieces of row antenna control units are connected to said m₂ pieces of antenna terminals of said column antenna control unit, respectively.
 11. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes between the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are connected via a through hole that passes through the ground conductor; and a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer; said antenna control unit is a two-dimensional antenna control unit including m₂ pieces of row antenna control units and one column antenna control unit; said M₂ pieces of row antenna control units are said antenna control unit of claim 9 including m=m₁ antenna terminals, where m₁ is an integer; said column antenna control unit is said antenna control unit of claim 9 including m=m₂ antenna terminals, where m₂ is an integer; and feeding terminals of said m₂ row antenna control units are connected to said m₂ antenna terminals of said column antenna control unit, respectively.
 12. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are electromagnetically connected via a coupling window that is formed in the ground conductor; a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer; said antenna control unit is a two-dimensional antenna control unit including m₂ row antenna control units and one column antenna control unit; said m₂ row antenna control units are said antenna control unit of claim 9 including m=m₁ antenna terminals, where m₁ is an integer; and said column antenna control unit is said antenna control unit of claim 9 including m=m₂ antenna terminals, where m₂ is an integer; and feeding terminals of said m₂ row antenna control units are connected to said m₂ antenna terminals of said column antenna control unit, respectively.
 13. An antenna control unit including: a feeding terminal to which a high-frequency power is applied; a feeding line that branches off into m pieces of lines at a k-th branch stage from said feeding terminal when m=2^(k), where m and k are integers; m pieces of antenna terminals for connecting antenna elements, which are provided on ends of said m pieces of feeding lines and arranged in a row; M_(k) pieces of positive beam tilting phase shifters, where M_(k)=M_((k-1))×2+2^((k-1)) when k≧1 and M₁=1, which all have the same characteristics and electrically change a phase of a high-frequency signal that passes through said feeding line in a positive direction; and M_(k) pieces of negative beam tilting phase shifters which all have the same characteristics and electrically change the phase of the high-frequency signal that passes through said feeding line in a negative direction, wherein: said positive beam tilting phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said positive beam tilting phase shifters which are located between an (n+1)-th antenna terminal, where n is an integer from 1 to m−1, and said feeding terminal is one larger than the number of said positive beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal; and said negative beam tilting phase shifters are placed at some positions on said feeding line that branches off into m pieces of lines, such that the number of said negative beam tilting phase shifters which are located between an n-th antenna terminal to said feeding terminal is one larger than the number of said negative beam tilting phase shifters which are located between an (n+1)-th antenna terminal to said feeding terminal.
 14. A two-dimensional antenna control unit including: m₂ pieces of row antenna control units and one column antenna control unit, wherein: said m₂ pieces row antenna control unit are said antenna control unit of claim 13 including m=m₁ pieces of antenna terminals, where m₁ is an integer; said column antenna control unit is said antenna control unit of claim 13 including m=m₂ pieces of antenna terminals, where m₂ is an integer; and said feeding terminals of said m₂ pieces of row antenna control units are connected to said m₂ pieces of antenna terminals of said column antenna control unit, respectively.
 15. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material; the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are connected via a through hole that passes through the ground conductor; a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer; said antenna control unit is a two-dimensional antenna control unit including m₂ row antenna control units and one column antenna control unit; said m₂ pieces of row antenna control units are said antenna control unit of claim 13 including m=m₁ antenna terminals, where m₁ is an integer; said column antenna control unit is said antenna control unit of claim 13 including m=m₂ antenna terminals, where m₂ is an integer; and feeding terminals of said m₂ row antenna control units are connected to said m₂ antenna terminals of said column antenna control unit, respectively.
 16. A phased-array antenna that includes, on a dielectric substrate: plural antenna elements; and an antenna control unit having a feeding terminal to which a high-frequency power is applied, and phase shifters that are connected with the respective antenna elements by feeding lines which branch off from said feeding terminal and electrically change a phase of a high-frequency signal that passes through the respective antenna elements and said feeding terminal, said phase shifters being placed at some positions on the feeding lines, wherein: each of said phase shifters includes a hybrid coupler on a paraelectric transmission line layer that employs a paraelectric material as a base material, and a stub on a ferroelectric transmission line layer that employs a ferroelectric material as a base material, the paraelectric transmission line layer and the ferroelectric transmission line layer are laminated through a ground conductor, and said hybrid coupler and said stub are electromagnetically connected via a coupling window that is formed in the ground conductor; a distance between conductors that form a transmission line on the ferroelectric transmission line layer is larger than a distance between conductors that form a transmission line on the paraelectric transmission line layer; said antenna control unit is a two-dimensional antenna control unit including m₂ row antenna control units and one column antenna control unit; said m₂ row antenna control units are said antenna control unit of claim 13 including m=m₁ antenna terminals, where m₁ is an integer; said column antenna control unit is said antenna control unit of claim 13 including m=m₂ antenna terminals, where m₂ is an integer; and feeding terminals of said m₂ row antenna control units are connected to said m₂ antenna terminals of said column antenna control unit, respectively. 